3. The arm contains the following parts:
1. Balance wheel: It is a wheel with shining surface, at the right side
of the head which is driven by handle or belt. The whole machine is
made operational by the rotation of the balance wheel.
2. Tension regulator: This is a mechanism fixed to the face plate for
controlling the tension on the upper thread. Two concave discs are
put together with their convex sides facing each other. The upper
thread is made to press through these discs and the pressure of
the discs on the thread is adjusted with a spring which is tightened
or loosened with the help of a screw.
4. 3. The thread take-up lever: It is a lever located above the tension
regulator which moves up and down as the balance wheel is
rotated. The axle of the wheel brings lever into motion. At the outer
end of the lever, there is a hole through which the upper thread
coming from tension regulator passes. It pulls the required amount
of thread from the tension regulator and feeds it to the needle as it
moves down. Then it moves up to tighten the loop formed by the
shuttle, to form a firm stick.
The needle bar: It is an upright bar at the lower end of which the
needle is attached. It also moves up and down as the machine
operates and carries needle down to the shuttle through the fabric
to make the loop of the thread and then brings it back
5. 5. The presser foot: It is a detachable
device which holds the fabric in place on
the feed dog while stitching. This device is
not used when other attachments for
tucks, ruffles or embroidery are used.
6. 6. The presser foot lifter: It is the lever attached to
the presser bar to control the up and down moment
of the presser foot. It must always be lifted to take
out the material from the machine.
7. Pressure regulating screw: It is a screw above the
presser bar which can be tightened to increase the
pressure on the fabric while working with fine fabric
and loosened to accommodate thick fabric.
7. 8. The stitch regulator: It is a lever attached to the screw
that helps to regulate the length of the stitches according
to the type of fabric to be sewn. The length of the stitch
is determined by the markings indicated on its side.
8. 9. Bobbin winder: It is a simple mechanism
for winding thread on the bobbin and is
located at the right side of the arm near
the wheel.
10. Bobbin winder tension angle: It is a
device situated near the bobbin winder
which helps to wind the bobbin evenly.
9. 14. Spool pins: These are the upright metal
rods fitted on top of the arm to hold the
thread spool.
15. Handle driver: It is attached to the
handle attachment of the machine and
helps to drive it with hand.
10. Bed of the machine contains the
following parts:
1. Needle or throat plate: This is a semi-circular disc with highly
smooth and shining surface. It has a hole to allow the needle to
pass through it. The plate provides a leveled surface for the cloth
to move as it is being stitched and also protects the lower part of
the machine from dirt.
2. Hinged bed plate: It flips up and down for inserting or removing
the bobbin into the shuttle. In some machines, the bed plate slides
down.
3. Feed dog: It is a small device with teeth wic carries the material
backward as it is being stitched. It moves upward as the machine
is operated, the material advances as each stitch is made.
11. 4. Shuttle: It holds the bobbin and moves to form the loop as the machine is
operated. It is fitted below the feed dog or to its left side.
5. Treadle drive: It is a large wheel located under the board in the treadle
machine. It is connected to the balance wheel with a leather belt. As it
rotates, the power is transmitted to the balance wheel by the leather belt.
6. Treadle: It is the foot rest at the base of the treadle machine which is
pressed with feet to operate the treadle machine.
12. Special attachments or
Accessories
A number of remarkable little steel attachments are available that can
be quickly and easily snapped into place to perform a variety of jobs
within minutes, which otherwise take a long time. The following
accessories increase the machines versatility and efficiency.
1. Stitch pattern cam: This is a device inserted in the machine to produce
various stitch patterns e.g. zig zag patterns. It may be inbuilt or
inserted. The cam helps to move the needle side to side while the stitch
width regulator decides the maximum width of the pattern. At the same
time needle bar also moves up and down as usual to form lock stitches.
There are special cams for making buttonholes also.
13. 2. Zipper foot: It is used to stitch a seam in which there is more bulk
on one side than the other e.g. zipper insertion, covering a cord,
sewing bound buttonholes. It is so designed that the needle can sew
very close to the zip teeth.
3. Zigzag foot: It is also called all-purpose foot. It is used primarily to
plain zigzag stitching but can also be used for straight stitching.
14. 4. Embroidery foot: It can be used for making decorative
stitch patterns. The bottom of the foot is so designed that
it permits the stitch stitches of embroidery to pass
through the foot.
5. Seam gauge: It is attached to the machine bed and
adjusted to maintain a specific distance between the
edge and the needle.
15. 6. Blind hemming guide: It is attached to the presser foot
to old garment and hem edge in place.
7.Other presser foot attachment are pin tuck foot,
buttonhole foot, button foot etc.
